One of Prime Minister Benjamin Netanyahu’s closest confidants has turned state witness and will incriminate him in corruption allegations,Israeli media has reported.

It is the latest in a series of developments that threaten to topple the beleaguered Israeli leader.

Police would not confirm whether long-time aide Shlomo Filber would give evidence against Mr Netanyahu, but all the major Israeli media outlets said a deal to do so had been reached.

Mr Filber, former director of the Communications Ministry under Mr Netanyahu, is under arrest on suspicion of promoting regulation worth hundreds of millions of dollars to Israel’s Bezeq telecom company. In return, Bezeq’s popular news site, Walla, allegedly provided favourable coverage of Mr Netanyahu and his family.

The reports came shortly after another bombshell allegation that a different longtime confidant attempted to bribe a judge in exchange for dropping a corruption case against Mr Netanyahu’s wife.

The prime minister, who held the communications portfolio until last year, has not yet been named as a suspect, though he may soon be questioned. Mr Netanyahu has denied all the charges, calling them part of a media witch hunt, and has vowed to carry on.

Nevertheless, the string of accusations appears to be taking its toll.

Senior Cabinet ministers from his ruling Likud party, who until recently have marched out dutifully to defend him, have largely gone silent.

Mr Netanyahu himself appeared ashen in video released late on Tuesday calling the claims “total madness”.

Aluf Benn, editor-in-chief of the Haaretz daily, wrote on Wednesday that “these are the final days of Benjamin Netanyahu’s rule”.

Other leading columnists suggested that if Mr Filber told all he knew, Mr Netanyahu was probably more worried about avoiding prison than staying in office.

“When so many dark clouds accumulate in the sky, the chances of rain increase,” wrote Nahum Barnea in Yediot Ahronot.

“His appearance lent the fight he is waging the dimensions of a Shakespearean tragedy. This isn’t the end. It isn’t even the beginning of the end. But it cannot have a different end.”

The latest probes come days after police announced that there was sufficient evidence to indict Mr Netanyahu for bribery, fraud and breach of trust in two separate cases.

Attorney General Avihai Mandelblit, a Netanyahu appointee, will make the final decision on whether to file charges – a process that is expected to take several months.

Mr Netanyahu is accused of receiving lavish gifts from Hollywood mogul Arnon Milchan and Australian billionaire James Packer.

In return, police say Mr Netanyahu operated on Mr Milchan’s behalf on US visa matters, legislated a tax break and connected him with an Indian businessman.

In the second case, Mr Netanyahu is accused of offering a newspaper publisher legislation which would weaken his paper’s main rival in return for more favourable coverage.